<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .parent{
            position: fixed;
            top: 10px;
            left: 10px;
            width: 100px;
            height: 100px;
            background-color: #eee;
        }
        .child{
            position: absolute;
            width: 50px;
            height: 50px;
            background-color: red;
            top: 10px;
            left: 10px;
        }
        /* .f_parent{
            width: 200px;
            background-color: red;
            overflow: hidden;
        }
        .f_child{
            width: 100px;
            height: 100px;
            background-color: blue;
            float: left;
        } */
    </style>
</head>
<body>
    <p>dsadsadsadsadsadsaddsadsadsadsadsadsad</p>
    <br><br><br><br><br>
    <p>dsadsadsadsadsadsaddsadsadsadsadsadsad</p>
    <br><br><br><br><br>
    <p>dsadsadsadsadsadsaddsadsadsadsadsadsad</p>
    <br><br><br><br><br>
    <p>dsadsadsadsadsadsaddsadsadsadsadsadsad</p>
    <br><br><br><br><br>
    <p>dsadsadsadsadsadsaddsadsadsadsadsadsad</p>
    <br><br><br><br><br>
    <div class="parent">
         <p>test</p>
        <div class="child"></div>
    </div>
    <!-- <div class="f_parent">
        <p>dsadsadsadsadsadsaddsadsadsadsadsadsad</p>
        <div class="f_child">
            test
        </div>
    </div> -->
</body>
</html>